1. Health
Vincent Iannelli, M.D.

California Mumps Outbreak

By December 7, 2012

Follow me on:

The CDC has issued its report on the mumps outbreak at Berkeley last year.

While we initially heard of two confirmed cases and a third suspected case of mumps, the CDC report, "Mumps Outbreak on a University Campus - California, 2011," adds another 26 cases to the outbreak, which lasted from August 25, 2011 to January 7, 2012.

As with many of the recent measles outbreaks in the United States, this mumps outbreak started with an unvaccinated student traveling to Europe. He returned, got sick, and proceeded to directly and indirectly get an additional 28 people sick, including four who developed orchitis (testicular inflammation).

The report highlights several important things, including that:

  • vaccinated people can still get mumps when they have extended person-to-person contact with someone who is sick with mumps.
  • accurate diagnosis of vaccine-preventable diseases can be delayed as vaccines have done such a good job of preventing them in most communities. Instead of mumps, the first patient was diagnosed with cellulitis and it wasn't until he later developed testicular pain that doctors suspected mumps.
  • reporting of vaccine-preventable diseases to local and state health departments, which can help to control outbreaks, can also be delayed. It wasn't until at least two generations of transmission had occurred that the health department in California was finally notified.
  • colleges that don't require proof of having had the MMR series make it difficult to target immunization of unvaccinated or undervaccinated students to help control an outbreak.

In addition to encouraging everyone to get fully vaccinated, especially matriculating students who should have documentation of receipt of 2 doses of MMR before entering college, the CDC report advises that "heightened clinical awareness of mumps, appropriate testing, and rapid reporting of suspected cases to public health authorities is essential for limiting outbreaks."

Kids have plenty to do and worry about when they get into college. They shouldn't have to worry about getting mumps from someone in their dorm too.

Follow us on Twitter and Facebook
Stories about Vaccine Preventable Diseases
Vaccine Preventable Diseases
Measles Outbreaks
Vaccine Facts

December 7, 2012 at 9:46 pm
(1) PutinReloaded says:

Vaccine failure isn’t vaccine failure. It is always because some people don’t vaccinate. And medical inability to diagnose isn’t incompetence.

December 7, 2012 at 11:27 pm
(2) brenda says:

so if i am vaccinated why do i still get the illness that i was vaccinated for??? so i see it that vaccines dont work. all they really seem to do is fill a body with toxins. whooping cough seems to be prevalent in many places these days and those i know to have been vaccinated sem to get it worse than the odd one i know of that wasnt vaccinated. how is this??? Why do we vaccinate for illnesses that dont actually do us any long term harm and why do we vaccinate babbies for diseases that are transmitted sexually??

December 8, 2012 at 12:21 am
(3) Twyla says:

Merck Overstated Mumps Vaccine Effectiveness?

Whistleblower lawsuit against Merck

In the old days, i.e. in my generation, people mostly came down with mumps as children, and this immunity lasted much longer than the vaccine-induced immunity. When I was in college, we didn’t have any mumps outbreaks.

There are arguments which can be made in favor of vaccinating against mumps, but if vaccinated college kids are coming down with mumps don’t blame that on the unvaccinated.

I do agree though that heightened clinical awareness of mumps, appropriate testing, and rapid reporting are important.

December 8, 2012 at 3:03 am
(4) michelle says:

Are there really readers in this world that will believe this garbage if written in a authoritive tone – without any quotes citations or references to what the author is talking about. You state that it started with an unvaccinated student. Did this information come from a valuable source? If so there would be a way to reference what you are talking about. I learned how to use references in high school.

December 8, 2012 at 10:33 am
(5) Myth Buster says:

Here is the link for Michelle who apparently was taught how to use references in high school, but failed reading comprehension. The reference is within the text of the blog: “the CDC report, “Mumps Outbreak on a University Campus – California, 2011,” adds another 26 cases to the outbreak, which lasted from August 25, 2011 to January 7, 2012.”


While it would be nice if Dr. Iannelli provided the hyperlink, it is incorrect to say he didn’t reference his source. He did. Michelle just didn’t understand what she was reading.

December 12, 2012 at 9:55 am
(6) Cassa says:

Hi Mythbuster; actually from reading the article the unvaccinated person was just “assumed” to be the cause; he was never tested.
Second generation transmission means vaccinated people were giving it to vaccinated people…
One wonders how often this has happened in the past and it has been diagnosed as something else.On the up side,Twyla, there is probably more natural immunity ( fropm undiagnosed infection and recovery) out there than people guess,which as you pointed out is likely to have a much more protective effect for the herd as a whole.

December 12, 2012 at 11:29 am
(7) Myth Buster says:

Hi Mythbuster; actually from reading the article the unvaccinated person was just “assumed” to be the cause; he was never tested.

Did I say otherwise, Cassa? No, I just provided the link, which Michelle was unable to find on her own.

Second generation transmission means vaccinated people were giving it to vaccinated people…

No vaccine is 100% effective, so it would be expected that vaccinated people could transmit to other vaccinated people for which the vaccine failed. The unvaccinated person was the presumed source of the infection since this student was known to be susceptible, traveled to an endemic area, was the first case of mumps, the other students had contact with the unvaccinated student and their illness occurred after this unvaccinated student. How else could one explain the epidemiology of this outbreak if the unvaccinated student was not the source of the infection?

December 12, 2012 at 1:47 pm
(8) Cassa says:

To paraphrase Dr Ianellis comments; vaccinated people can still get mumps and there are difficulties with accurate diagnosis.
So..any vaccinated person at that school could also have been the first case; one wonders how many cases of “swollen lymph nodes”, “viral infections’ and “cellulitis” had previously occured before mumps was identified..
Maybe that young man was the first case; but given that he has not even been proved to have had it at all, and that we have already discovered vaccinated people transmit the disease too;it is a guess without much substance at this point.

December 12, 2012 at 8:37 pm
(9) Myth Buster says:

I don’t know, as it seems that there is a lot more evidence to support the CDC’s guess, then yours, which is pure speculation and not supported by the facts of the cases. I think you have forgotten to count for the incubation period of the virus and how that relates to the start of school.

You are basically saying that the investigation missed a previous case in a vaccinated person that then gave it to the unvaccinated person at the same time he traveled to an endemic area.

Even if you were correct, it doesn’t change the fact that the unvaccinated student brought the virus to campus with him which then spread to 28 other people. The epidemiological curve in the report shows this.

Mumps was identified by PCR and then traced back to the unvaccinated student by looking for cases of “swollen lymph nodes” etc. That’s how they found the presumed index case. The cases that weren’t lab confirmed where epidemiologically linked. Although, I agree, it was a shame that the unvaccinated student did not get the the tests requested by the doctor, so we’ll never know for sure. However, the available evidence is pretty incriminating, especially in the absence of a plausible alternative. Further, it really doesn’t matter if the unvaccinated student was the index case or not, since the conclusions of the report were not dependent on that.

Leave a Comment

Line and paragraph breaks are automatic. Some HTML allowed: <a href="" title="">, <b>, <i>, <strike>
  1. About.com
  2. Health
  3. Pediatrics

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.